The mercury-containing products, which were not manufactured in the United States, have been found in at least seven states. The FDA typically does not allow mercury in drugs or cosmetics.

The agency advises that consumers discontinue use of products that contain "mercurous chloride," "calomel," "mercuric," "mercurio" or "mercury." If ingredients are not listed on a product, the product should not be used, say FDA officials.

According to Scott Plensdorf, M.D., of Flint, Mich., patients at risk for using these products are usually teens and women. He recommends that physicians talk with their patients about "the need to be informed consumers with all skin care products to prevent potential serious health consequences to both them and their families."

Symptoms of mercury poisoning can include numbness or pain in certain areas of the skin and uncontrollable shaking or tremors, says the NIH(www.nlm.nih.gov).

Plensdorf says that for creams to be effective, they likely will have to be used for several months, leading to repeated exposures. And mercury poisoning is not the only possible effect of using untested products.

"Since the active ingredients haven't even been tested to determine their concentration, I worry that significant adverse effects, such as dermatitis and burning of the skin and mucous membranes, may occur," he notes.